ANALYSIS OF PP AND PS AMPLITUDE VARIATION WITH OFFSET

Abstract

In the present dissertation an attempt has been made for the analysis of PP and PS amplitude variation with offset for various lithological models relevant to hydrocarbon exploration. Synthetic seismograms have been generated for the models under consideration to study the amplitude variation with offset, both for PP and PS waves. The synthetic seismograms have been generated based on Zoeppritz equations. Following this, inversion of reflection amplitudes in the synthetic seismograms has been carried out to obtain the P wave velocity, S wave velocity and the density. The inversion has been carried out using three methodologies. The first method is based on carrying out a direct inversion, separately for PP and PS waves, using the Aki and Richards' approximations to the Zoeppritz equation. The second method consists of a two term joint inversion method which has been tested. The fmal method is a three term joint inversion method. The results of the inversions indicate that all the three model parameters, viz., P wave velocity, S wave velocity and the density are inverted satisfactorily by the different inversion methods. Using the PS data set in conjunction with PP data sets can improve the AVO inversion results in some cases.